1121 SE EVERETT MALL WAY SNOPAC 2019-01-29

t S ' • . Lateral Force Bracing(figures 2 and 3) o ;e Bracing a Ceilings constructed of lath and plaster or gypsum board,screw or nail at- tached to suspended members that support a ceiling on one level extending • from wall to wall shall be exempt from the lateral force bracing requirements. has \ia5^or less Source CISCA zones 3-4 a Lateral force bracing is the use of vertical struts(compression posts)and M V . splay wires(see figure 2). "' 7 2 gage \_� �� splayed • u ��. fir '. brace Lateral force bracing is required for ceilings ove 1,000 s.uare feet�nd not 45^or less )45^°rlas• wires required for ceilings less than 1,000 square feet proVr•e. ey are surroundec by four walls and braced to structure"Source ASCE 7-02 section 9.6.2.6.2.2 item c a Lateral Force Bracing shall be 12 feet on center(maximum)and begin no Cross tee ' Main beam farther than 6 feet from walls.Source CISCA Seismic zohes 3-4 -• a Splay wires are to be four 12 gage wires attached to the main beam.Wires are arrayed 90°from each other and at an angle not exceeding 45°from the • plane of the ceiling.Source CISCA Seismic zones 3-4 • Splay wires-are to be within 2 inches of the connection of the vertical strut to suspended ceiling.Source CISCA Seismic zones 3-4 Rigid bracing may be used in lieu of splay wires.source ASCE section 9.6.2.6.2.2 figure 3 Maximum Recommended Lengths for a Ceilings with plenums less than 12 inches to structure are not require to��, Vertical Struts • have lateral force bracing.source Portland Building Department Vertical struts must be positively attached to the suspension systems and t EMT CONDUIT structure above.Source CISCA 3-4 uto6'0" a The vertical strut may be EMT conduit,metal studs or a proprietary Comptes /z" EMT conduit psion post(see figure 3). 3/4"EMT conduit . up to 8'6" _ -- __ 4 t=MT conduit up to 10 0 Wail Moidinas(figure 4) ®. •! •2 F ¢ - ' r.'� l �- ihr �J _ _ -• ^ 1.(�./NII.'L'lnif i:";`'�(perimeter(`I�1C141Yp;�L"{�Ir;CI'�•1:?YP.fYI IIY.EPf:'I 1'.!1�'L'.iVP�)„hnri7nnin : flange 2 inches wide,unless•alternate methods are approved prior to instal- . 15/e"metal stud(25 gage) up to 6'2" latioh by the local building department and the designer of record. One end tol0'6" of the ceiling grid shall be attached to the wall molding,the other end shall 2'/z'metal stud(25 gage) up • have a 3/4 inch clearance from the wall and free to slide.Source ASCE 702 section Source Portland Building Department 9.6.2.6.2.2 item b rivets or approved • • The grid shall be attached at two adjacent walls(pop Note:Plenum areas greater than 11'0"will require method).Source CISCA Seismic zones 3-4 engineering calculations. a , There shall be a minimum 3/4 inch clearance from the end of the grid system at un-attached walls.Source ASCE 702 section 9.6.2.6.2.2 item b • • • Spreader Bars (figure 4) ° • Spreader(spacer)bars or other means approved by.local building depart- • , ment shall be used to prevent the ends of the main beams at perimeter walls fig Wall Moll• ding • Requirements are 4 � � from spreading open during a seismic event.Perimeter wires shall not be-in Wlieu of spreader bars.Source CISCA Seismic zones 3-4 r�) 4-r, "Nu. • a Wire tying is an acceptable alternative to spreader bars. /fs maximum e' 202 mm7 a Spreader bars are not required if a 90 degree intersecting cross or main is WALL /// within 8 inches of the perimeter wall. • I I Spreader bar or — • `° other suitable 5a and 5b) D sYstemrequiredto anger (Suspension) Wires (figures • S �� i keep Penmiter ' ///\ components from ,,� spreading apart / / unattached h mm) ... . a Hanger and perimeter wires must lie,plumb within 1 in 6 unless(figure 5a) X. at unattached Walls minimum ~4 2"(50 mm) O`°� counter sloping wires are provided(figure 5b),Source ASTM c 636 section 21.4 ` _ ...cisHanger.wires shall be 12 gage and spaced 4 feet on center or 10 gage ( spaced 5 feet on center:source ASTM C 636 • Any connection device at the supporting construction shall be capable of ca rying not less than 100 pounds.source CISCA zones 3-4 f